WARNING: When you sign into Google using your phone(like to get an app from their app store), Google claims all the contacts on your phone, and all your appointments belong to them and not to you. Please at least back them up locally before you sign in, and again before you sign out, as Google will DELETE them from your phone.
If you don't want Google even seeing your contacts/appointments and still want to sign in, make a local backup copy(off your phone?) of your contacts/appointments and then delete the non-backups before signing in. "What has seen can't be unseen"
Google probably has your phone number(from friends/co-workers) even if you didn't directly give it to Google.
P.S. Anybody want to sue Google for deleted contacts/appointments?